The present invention relates in general to a motion control device in the form of a friction hinge having two degrees of freedom. More specifically, the present invention relates to a gimbal mechanism in which the two degrees of freedom are about two orthogonal axes. One of the features of the present invention is the incorporation of a drag friction component in order to create a “non-symmetrical” gimbal behavior. In one embodiment of the present invention, the drag friction component is provided by a pair of hexagonal spring sleeves.
While the present invention has broad application in a variety of fields for a variety of different devices, one embodiment of the present invention is described in the context of a fluid control valve. Other devices and applications for the friction hinge of the present invention include mechanical connections such as swivel joints where wobble might be a concern. For example, the present invention would have applicability as part of a device where there is movement of one portion relative to another, typically stationary, portion and a desire to add a frictional force that exceeds the gravitational force. In this way, the added friction that has to be overcome to initiate movement is designed to prevent wobble of the movable portion.
Considering the use of the present friction hinge invention in the context of a fluid control valve, it will be noted that single-handled water faucet control valves have been offered with different mechanical arrangements for controlling the available directions of travel, the range of motion and the type or style of motion for the handle. One style of control valve of the type being described includes a handle that is moved in a generally sideways (left-to-right and right-to-left) direction in order to adjust the mix of hot and cold water for the desired temperature. With this style of water faucet control valve arrangement, the handle is typically moved in an upward or forward direction, away from the user, to increase the flow rate and volume. The handle is typically moved in a downward or rearward direction, toward the user, in order to reduce the flow rate and volume or to completely shut off the flow of water out of the controlled faucet.
Single-handled control valves of the type described above can be referred to as having a joy stick control handle due to the single-handle construction and the manner in which the handle can be moved. The directions and range of motions are controlled by the internal structure of the valve mechanism and by the selection and arrangement of the component parts. Some of these referenced component parts include the component parts of the friction hinge according to the present invention. Single-handled water faucet control valves that are known to exist are typically constructed with consideration given to the type of fluid to be delivered, the end use, the end user, and the circumstances that exist when the valve is actuated or opened relative to the convenience and safety of the user.
In the field of water delivery faucets, one style of single-handled control valve (referred to herein as “type one”, for reference only) is configured such that there is sliding motion in a first direction and rotary motion in a second direction. With a type one style of control valve, the selected water temperature is able to be maintained as the water flow is adjusted or turned off. This is possible because the first direction of motion is “decoupled” from the second direction of motion.
Another style of single-handled control valve (referred to herein as “type two”, for reference only) is configured such that the motion in a first direction and the motion in a second direction are not decoupled. This means that movement of the handle in a direction that is a vector product of the two primary directions is possible. In one specific configuration of a type two control valve, the handle returns to the center or neutral temperature position when the water flow is turned off. One embodiment of a type two style utilizes a modified ball and socket combination with a pin and slot feature to control the “return to neutral” characteristic as described above. Some of the branded DELTA® faucets, offered by Delta Faucet Company of Indiana, are designed in this manner.
The type one style involves movement of the handle in two different directions that are distinct from each other. As used herein, the term “distinct” is intended to define a control valve motion wherein movement of the handle in one direction to control or adjust one of the two water variables does not have an effect on the other water variable, and vice versa. More specifically, control valves of this style include a structure that enables rotary motion in one direction for controlling one water parameter and sliding motion in a second direction for controlling a second water parameter. Control valves of this type incorporate a front-to-back (or a back-to-front) tilting or sliding action for the ON-OFF control and rotation about a control axis for the HOT-COLD adjustment. The referenced “control” axis may be a vertical axis in certain faucet designs, and/or the Z axis depending on the faucet design, and/or the longitudinal axis of the valve body or handle. The mechanisms or arrangements that are selected for fluid control in this type or style of control valve inherently have high frictional interfaces and an effort is made in the nature of design modifications to try and reduce those frictional forces so that the control lever is able to move more easily.
There are aspects of fluid control valves that include the type one style of motion that can be improved upon. For example, the structure of this style and the mechanisms used to effect motion in the first and second directions make it progressively harder to manipulate flow temperature as the control valve approaches its full ON position. This is true due to the fact that the moment arm of the lever around the flow control axis typically decreases when the flow lever is in the ON position. It is also typically harder to control the flow rate as the temperature approaches either of the extreme positions (full hot or full cold) since the lever has usually rotated around to a less favorable position at these extremes as compared to the more optimized warm position. One benefit, however, of the type one style of motion is that this arrangement provides for a desirable decoupling of control motions for the two water flow variables, namely the water flow rate and the water temperature. These two variables can be easily controlled independently of one another by this type one style of motion.
When a fluid control valve is used for the delivery and control of water for a residential user, user convenience and safety are important. With the type one style of control valve, when the handle is moved to an “off” position, but with the water temperature position remaining elevated, the user can initially receive water at a higher temperature than desired. The type two style avoids the initial delivery of higher temperature water by returning the control lever to a temperature-neutral position when the flow of water is turned off. However, the type two style introduces a new consideration. Due to the freedom of movement of the fluid control valve and the different directions of travel, one for adjusting the water temperature and the other for adjusting the flow rate (volume), the user needs to carefully position the handle for the desired balance of both water temperature and water flow rate. For example, after the selected balance of temperature and flow rate is reached and thereafter an increased flow rate is desired, care must be taken to avoid changing the temperature as the handle is moved in order to adjust the fluid flow rate. A similar consideration exists once the desired flow rate is set and then the water temperature needs to be adjusted. While the freedom of handle movement does not present a safety concern, some potential purchasers of water faucets of this general type may prefer to be able to adjust one water parameter, temperature or flow rate, without unintentionally changing the other water parameter.
One reality of the type two style that includes a modified ball and socket is that with the ball at rest, there is static friction that influences the initial force that is required to “break” the ball free and initiate movement. Once the ball is in motion, the user feels the effect of dynamic friction and the dynamic friction is less than the static friction that had to be overcome to initiate movement. Since the type two style does not decouple the motion or travel in a first direction from the motion or travel in a second direction, once the static friction on the ball is overcome, it is difficult for the user to feel any difference in the two directions of motion or in a combination of those two directions, such as the vector product. Even if the user has selected one direction as his “preferred” direction of movement, it is difficult to sense or feel if there is any departure from the chosen path. Since the directions of motion or travel are not decoupled, breaking the ball free to initiate movement in one direction also breaks the ball free in the other direction.
After reviewing existing motion control mechanisms generally and those types used for fluid control valves, the features of interest or importance to consumers and the available products, the present inventors concluded that it would be an improvement to such motion control mechanisms if an improved friction hinge could be designed. One application for such an improved friction hinge would be in cooperation with a fluid control valve. The present inventors also envisioned that it would be an improvement to fluid control technology if the benefits and advantages of single-handle controlled motion could be combined with the decoupled control of the two water flow variables, temperature and flow rate, similar to the type one style of motion. The present inventors further envisioned that, by using the improved friction hinge, the structural configuration of the fluid control valve mechanism would have two decoupled directions of handle movement about two intersecting orthogonal axes and that the frictional force in one direction of handle travel would be different from the frictional force in the other direction of handle travel.
The present inventors envisioned that by selecting a modified ball and socket configuration, the realities of static friction versus dynamic friction could be utilized. With decoupled directions of travel, once the user selects the “preferred” direction of travel and initiates motion, the static friction is overcome and changes to the lower dynamic friction. This does not affect the other direction of travel which remains in a static friction state. The result, due to the lower frictional level, is that the control handle is easier to move in the selected (i.e., preferred) direction. The control valve prefers this direction as well since there is less friction. Whichever one of the two decoupled directions of travel is initially selected by the user, this is the direction that will provide a sense or feel to the user of a lower dynamic frictional force or frictional level. This then becomes the frictional drag that is sensed in order to continue with the selected direction of travel. Accordingly, it will be easier to continue moving the control handle in that preferred direction as compared to changing to the other direction. Any change to the other direction would then have to overcome the higher static friction in order to initiate movement.
The present inventors also considered as part of the friction hinge design the possibility of selectively increasing the friction for one direction of travel so that the other direction would be preferred, regardless of the static friction versus dynamic friction difference. For example, if it is preferred for the adjustment of the water flow rate to be easier, i.e., a lower frictional force, than the adjustment of the water temperature, i.e., a higher frictional force, then a fluid control valve could be designed as one application for the friction hinge of the present invention. If this described situation is preferred, then the frictional drag that is added to the water temperature direction must be greater than the static/dynamic difference. In this way, even if the water temperature direction is selected and the lower dynamic friction is encountered, the added frictional drag will exceed this difference such that the water flow rate direction is still preferred. It was also envisioned by the present inventors that whatever mechanism would be used to vary the frictional force between the two directions of motion, that the frictional force level could be adjusted so that it could be specifically configured to each particular faucet and control valve configuration.
From the evaluation of existing technology by the present inventors, they conceived of the present invention as a novel an unobvious improvement to the current state of the art in the field of motion control devices. Specifically, the present invention utilizes a structural configuration with two separate orthogonal axes passing through a point with decoupled control of the movement about each axis. As an option, the frictional force about a selected axis can be selectively adjusted. What results is a friction hinge for a type one style, joy stick motion, based on a modified ball and socket configuration, that includes temperature memory and a higher frictional force in the direction of water temperature adjustment in order to “prefer” motion in the direction of flow rate or volume adjustment. While there are various applications for the friction hinge of the present invention, the selected application in the context of a fluid control valve provides a practical example of everyday use.
While the present invention is described in the context of the preferred embodiment, it is to be noted that the applicable scope of the present invention is broader.